Reaction Feasibility Flashcards
What is the standard enthalpy of formation?
The enthalpy change when one mole of a substance is formed from its elements in their standard states.
When is the standard state of a substance at its most stable state?
At a pressure of 1 atmosphere and at a specified temperature usually taken as 298 K
What is the symbol for standard enthalpy of formation?
ΔH°f
What is the standard enthalpy of a reaction formula?
ΔH° = ΣΔH°f(products) - ΣΔH°f(reactants)
What is entropy?
a measure of the degree of disorder of the system.
What is the relationship between disorder and entropy?
The greater the degree of disorder, the greater the entropy
What state has a low disorder?
Solids
What state has a high disorder?
Gases
What is the relationship between entropy and temperature?
Entropy increases as temperature increases.
When is there a rapid increase in entropy?
At the melting and boiling points
What does the second law of thermodynamics state?
The total entropy of a reaction system and its surroundings increases for a spontaneous process.
What increases the entropy of the surroundings?
Heat energy released by the reaction system.
What decreases the entropy of the surroundings?
Heat energy absorbed by the reaction system
What does the third law of thermodynamics state?
The entropy of a perfect crystal at 0K is zero
What is the standard entropy of a substance?
The entropy value for the substance in its standard state (1atm 298K)
